Method for providing composite image based on optical transparency and apparatus using the same

ABSTRACT

Disclosed herein are a method for providing a composite image based on optical transparency and an apparatus for the same. The method includes supplying first light of a first light source for projecting a virtual image and second light of a second light source for tracking eye gaze of a user to multiple point lights based on an optical waveguide; adjusting the degree of light concentration of any one of the first light and the second light based on a micro-lens array and outputting the first light or the second light, of which the degree of light concentration is adjusted; tracking the eye gaze of the user by collecting the second light reflected from the pupil of the user based on the optical waveguide; and combining an external image with the virtual image based on the tracked eye gaze and providing the combined image to the user.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of Korean Patent Application No.10-2017-0073944, filed Jun. 13, 2017, which is hereby incorporated byreference in its entirety into this application.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates generally to technology for providing acomposite image based on optical transparency, and more particularly toa method for providing a composite image based on optical transparency,in which, using a light and small device like eyeglasses, a virtualimage that fills a user's field of view may be provided along withsee-through vision to the real world without blocking a view of anexternal environment, and an apparatus for the same.

2. Description of the Related Art

Generally, 3D display techniques are largely categorized into thefollowing three types. The first one is a method for artificiallyimplementing a natural phenomenon in which light emitted from a lightsource (e.g. the sun) is reflected from a surface having a certainshape, and the reflected light, having a specific wavelength (color), isdirected to the eyes of an observer, for example, like an idealholographic display. The second one is a method for generating anddisplaying two images that artificially implement binocular disparity,which is the difference between images input to the left and right eyes,among the characteristics of human visual 3D recognition. The final oneis a method for implementing an effect similar to the effect of thefirst method by delivering multiple viewpoints to the user's eyes basedon the second method.

As described above, the conventional methods for implementing 3Dstereoscopic images may not realize an optical see-through capability,which enables users to freely see their surroundings as though lookingthrough eyeglasses.

Most lightweight Head Mounted Displays (HMDs) for supporting an opticalsee-through capability, introduced for customers in the market, have anarrow viewing angle that ranges from about 30 to 40 degrees. Accordingto a case study report, the maximum viewing angle of an opticalsee-through wearable display having an external form as light aseyeglasses is only 56 degrees, as described in the thesis titled“Wearable display for visualization of 3D objects at your fingertips”(written by Ungyeon Yang and Ki-Hong Kim and published in SIGGRAPH' 14ACM SIGGRAPH 2014 Posters).

Also, like the iOptik system developed by INNOVEGA, the method ofplacing a high-resolution micromini display panel very close to the eyeshas been proposed as a method for implementing a wearable display aslight as eyeglasses, but this method is problematic in that it isinconvenient because a user must wear a special contact lens.

Also, as proposed in a thesis titled “Pinlight displays: wide field ofview augmented reality eyeglasses using defocused point light sources”(written by Andrew Maimone, Douglas Lanman, Kishore Rathinavel, KurtisKeller, David Luebke, and Henry Fuchs and published in ACM Transactionson Graphics (TOG)—Proceedings of ACM SIGGRAPH 2014 TOG Homepage archive,Volume 33 Issue 4), the existing method for implementing a display inthe form of light eyeglasses is not satisfactory for use in commercialproducts for customers because of multiple disadvantages, such asnonuniformity of a light source of a backlight panel configured withpoint light sources, low quality of a provided image due to anincomplete eye-tracking function, and the like.

According to the conventional method, a panel for creating multiplepoint light sources called “pinlights” is formed by etching patterns atregular distances (by cutting grooves using a robot arm of a 3D printer)on an acrylic sheet, and a backlight panel is implemented in such a waythat, when light incident from edge-lit LEDs meets an etched divot whiletravelling after being totally internally reflected, the light isemitted outside the acrylic sheet via the point-type light. That is, theconventional method employs some backlight implementation methodscommonly used in the technical field for implementing a flat displaypanel, for example, an edge-lit screen, a lightguide, and the like.

Therefore, the conventional method is disadvantageous in that it isdifficult to implement point light sources having equal brightness (thesame amount of light) at all positions in a pinlight panel. Also,respective light rays emitted by multiple point light sources may havedifferent brightness and wavelengths. When a display panel for a TV ismanufactured, the corresponding problem may be solved by additionallyapplying a diffusion film for evenly diffusing light in between thefront point light source unit and a color pixel panel (e.g., an RGBpanel). However, this method is merely for acquiring the effect ofevenly emitting light from all parts of a flat panel, but is notsuitable for an optical see-through wearable display becausetransparency (a see-through effect) for penetrating a real (virtual)image outside the image panel is obstructed. In connection with this,Korean Patent Application Publication No. 10-2015-0026455 discloses atechnology related to “Apparatus and method for designing display foruser interaction in the near-body space”.

SUMMARY OF THE INVENTION

An object of the present invention is to provide technology for awearable display that is capable of providing image information fillinga user's field of view based on optical transparency using a light andsmall module resembling general eyeglasses.

Another object of the present invention is to improve the visualquality, such as contrast, color quality, intensity, focus alignment,and the like, of an image output via an eyeglasses-type display byproviding technology for controlling energy emission by each point lightsource, which may overcome the limitation of a pin-light array.

A further object of the present invention is to provide an eye-trackingmodule with a minimum volume that may be embedded in an eyeglasses-typedisplay and that may track the pattern of movement of an eye located infront thereof or off to one side.

In order to accomplish the above objects, a method for providing acomposite image based on optical transparency according to the presentinvention includes supplying first light of a first light source forprojecting a virtual image and second light of a second light source fortracking eye gaze of a user to multiple point lights based on an opticalwaveguide having a bidirectional propagation characteristic; adjusting adegree of light concentration of any one of the first light and thesecond light based on a micro-lens array and outputting the first lightor the second light, of which the degree of light concentration isadjusted; collecting the second light reflected from a pupil of the userbased on the optical waveguide and thereby tracking the eye gaze of theuser; and combining an external image with the virtual image based onthe tracked eye gaze and providing the combined image to the user.

Here, a transparent backlight panel including the optical waveguide, themicro-lens array, and a transparent image display panel for generatingthe virtual image may be included in a transparent panel of a wearabledisplay, which is located directly in front of the pupil of the user.

Here, supplying the first light and the second light may be configuredto individually control an intensity of the first light supplied to eachof the multiple point lights by adjusting diameters of some of multiplepaths corresponding to the optical waveguide.

Here, supplying the first light and the second light may be configuredto individually control a characteristic of the first light supplied toeach of the multiple point lights based on a multiple-layer structureusing multiple transparent backlight panels.

Here, the micro-lens array may be configured with multiple lenses,thicknesses of which are controllable in real time.

Here, the multiple lenses may be individually controlled based on acontrol signal for each of multiple groups generated based on themultiple lenses.

Here, the method may further include calibrating a focus of a compositeimage projected onto the pupil of the user using an additionalmicro-lens array located between the image display panel and the pupilof the user.

Here, the transparent panel may be in a form of a flat surface or acurved surface.

Here, outputting the first light or the second light, of which thedegree of light concentration is adjusted, may include performing, bythe micro-lens array, at least one of a convergence function and adivergence function, thereby adjusting the degree of light concentrationsuch that the first light has a same property as natural light; andperforming, by the micro-lens array, at least one of the convergencefunction and the divergence function, thereby adjusting the degree oflight concentration such that a transmissivity with which the secondlight penetrates through the image display panel is increased and suchthat a collection rate at which the second light reflected from thepupil of the user is collected is increased.

Here, outputting the first light or the second light, of which thedegree of light concentration is adjusted, may include deactivating alens, a refractive index of which exceeds a user recognition level,among the multiple lenses.

Here, tracking the eye gaze of the user may be configured to collect thereflected second light using an end part of the optical waveguide thatis extended so as to be closer to the pupil of the user.

Also, a wearable display based on optical transparency according to anembodiment of the present invention includes a transparent backlightpanel for supplying first light of a first light source for projecting avirtual image, which is to be combined with an external image, andsecond light of a second light source for tracking an eye gaze of a userto multiple point lights based on an optical waveguide having abidirectional propagation characteristic; a micro-lens array foradjusting a degree of light concentration of the first light and thesecond light; an eye-tracking module for tracking the eye gaze of theuser by collecting the second light reflected from a pupil of the userbased on the optical waveguide; and an image display panel fordisplaying the virtual image.

Here, the transparent backlight panel, the micro-lens array, and theimage display panel may be included in a transparent panel locateddirectly in front of the pupil of the user.

Here, the transparent backlight panel may individually control anintensity of the first light supplied to each of the multiple pointlights by adjusting diameters of some of multiple paths corresponding tothe optical waveguide.

Here, a characteristic of the first light supplied to each of themultiple point lights may be individually controlled based on amultiple-layer structure using multiple transparent backlight panels.

Here, the micro-lens array may be configured with multiple lenses,thicknesses of which are controllable in real time.

Here, the multiple lenses may be individually controlled based on acontrol signal for each of multiple groups generated based on themultiple lenses.

Here, the transparent panel may further include an additional micro-lensarray, located between the image display panel and the pupil of theuser, for calibrating a focus of a composite image to be projected ontothe pupil of the user.

Here, the transparent panel may be in a form of a flat surface or acurved surface.

Here, the micro-lens array may adjust the degree of light concentrationsuch that the first light has same properties as natural light byperforming at least one of a convergence function and a divergencefunction, and may adjust the degree of light concentration so as toimprove a transmissivity, with which the second light penetrates throughthe image display panel, and to improve a collection rate, at which thesecond light reflected from the pupil of the user is collected, byperforming at least one of the convergence function and the divergencefunction.

Here, the micro-lens array may deactivate a lens, a refractive index ofwhich exceeds a user recognition level, among the multiple lenses.

Here, the eye-tracking module may collect the reflected second lightusing an end part of the optical waveguide extended so as to be closerto the pupil of the user.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the presentinvention will be more clearly understood from the following detaileddescription taken in conjunction with the accompanying drawings, inwhich:

FIG. 1 is a view that shows the process of providing a composite imageusing a wearable display based on optical transparency according to anembodiment of the present invention;

FIG. 2 is a flowchart that shows a method for providing a compositeimage based on optical transparency according to an embodiment of thepresent invention;

FIGS. 3 to 6 are views that show an example of design of an opticalwaveguide based on multiple layers according to the present invention;

FIG. 7 is a view that shows an example of design of an optical waveguidebased on a single layer according to the present invention;

FIGS. 8 to 11 are views that show an example of design of shared ordistributed optical waveguides and the method of outputting energy basedthereon according to the present invention;

FIGS. 12 to 16 are views that show an example of the method ofcontrolling multiple lenses in a micro-lens array according to thepresent invention;

FIG. 17 is a view that shows an example in which the transparentbacklight panel illustrated in FIG. 6 and the micro-lens arrayillustrated in FIG. 14 are layered;

FIG. 18 is a view that shows the structure of a wearable display in theform of a flat surface according to an embodiment of the presentinvention;

FIG. 19 is a view that shows the structure of a wearable display in theform of a curved surface according to an embodiment of the presentinvention; and

FIG. 20 is a view that shows the structure of a wearable displayincluding an additional micro-lens array according to an embodiment ofthe present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will be described in detail below with referenceto the accompanying drawings. Repeated descriptions and descriptions ofknown functions and configurations which have been deemed to make thegist of the present invention unnecessarily obscure will be omittedbelow. The embodiments of the present invention are intended to fullydescribe the present invention to a person having ordinary knowledge inthe art to which the present invention pertains. Accordingly, theshapes, sizes, etc. of components in the drawings may be exaggerated inorder to make the description clearer.

Hereinafter, a preferred embodiment of the present invention will bedescribed in detail with reference to the accompanying drawings.

FIG. 1 is a view that shows the process of providing a composite imageusing a wearable display based on optical transparency according to anembodiment of the present invention.

Referring to FIG. 1, a wearable display 100 based on opticaltransparency according to an embodiment of the present inventionprovides a composite image 150, acquired by combining an external image110 visible in an external environment with a virtual image 130, towarda pupil 140 of a user, thereby showing the user the virtual image 130naturally superimposed over the real world. That is, FIG. 1 shows anexample in which the image of a flying butterfly is combined with theimage of a flower and is provided to the user, in which case the virtualimage 130, corresponding to the flying butterfly, may be provided bybeing output via the inner surface of the transparent panel 120 of thewearable display 100, which is placed directly in front of the pupil 140of the user.

The main components of the above-described lightweight wearable display100, which is capable of providing a natural composite image, mayinclude a transparent backlight module for supplying light by beingconfigured with an array of point lights based on an optical waveguide,an eye-tracking module for tracking the eye gaze of the user who wearsthe wearable display by being included in the transparent panel based onthe optical waveguide, an image display panel for displaying a virtualimage provided only to the user who wears the wearable display, and amicro-lens array for controlling the degree of concentration of lightemitted from the multiple point lights.

Here, commonly used infrared rays may be used to track the eye gaze of auser, but without limitation to a specific wavelength, any wavelengththat is harmless to the human body and available for eye tracking may beused.

Here, the example illustrated on the right side of FIG. 1 shows that auser recognizes the result of a combination of the virtual image 130,which is the image of a flying butterfly, with the external image 110,which is the image of a flower, as a single image, like the compositeimage 150.

Here, the external image 110 may be a real object in the real world oran image or video output via another arbitrary display, and the virtualimage 130 may be an image made visible only in the image display panelof the wearable display 100.

Here, the external image 110 may be projected onto a pupil 140 of a userthrough natural light 111, and the virtual image 130 may be projectedonto the pupil 140 of the user through visible rays 121 generated in thetransparent backlight panel.

Here, the transparent backlight panel may output infrared rays 122 fortracking the eye gaze of a user along with the visible rays 121 forprojecting the virtual image 130. The infrared rays reflected from apupil 140 of the user may be collected and used for tracking the eyegaze of the user.

Here, the light for tracking the eye gaze of a user is not limited toinfrared rays, and any light having a wavelength that is capable of eyetracking but is harmless to the human body may be used.

The wearable display 100 according to an embodiment of the presentinvention may be an optical system that uses the characteristics of apinhole camera model based on multiple point lights in order to enable auser to clearly show the image provided by a panel located directly infront of an eye of the user. Here, the distance from a pupil 140 of theuser to the transparent panel 120 of the wearable display 100 may beassumed to be about 2 to 3 cm.

Realization of a transparent backlight panel including a point-lightarray based on an optical waveguide, which is a core element of thepresent invention, may be assured through the adoption of a fabricationmethod through which an optical waveguide can be formed inside a thintransparent element such as a flexible film. Also, realization of aneye-tracking module using an optical waveguide may be assured throughthe method of forming a fixed micro-lens array or a deformable lensbased on a flexible transparent material such as a polymer.

FIG. 2 is a flowchart that shows a method for providing a compositeimage based on optical transparency according to an embodiment of thepresent invention.

Referring to FIG. 2, in the method for providing a composite image basedon optical transparency according to an embodiment of the presentinvention, first light of a first light source for projecting a virtualimage and second light of a second light source for tracking the eyegaze of a user are supplied to multiple point lights based on an opticalwaveguide having a bidirectional propagation characteristic at stepS210.

Here, the first light is not randomly reflected, but is supplied onlyalong a previously designed optical waveguide path, whereby the problemin which light cannot maintain an equal brightness and wavelength bybeing totally internally reflected and scattered when the existing pointlight source pattern is used may be solved.

For example, the optical waveguide may be designed and manufacturedusing the method of designing and manufacturing an Integrated Circuit(IC) board or a press-printing method for forming multiple layers. Thismanufacturing method is commonly used in optical communications fieldsor semiconductor fabrication fields, but may also be used to solve theproblems resulting from forming the pattern of point lights in the fieldof a wearable display that is capable of providing a composite image, asin the present invention.

Here, the first light may be visible rays for showing a virtual imagegenerated in a wearable display to a user by projecting the same.

Here, the intensity of the first light supplied to each of the multiplepoint lights may be individually controlled by adjusting the diametersof some of multiple paths corresponding to the optical waveguide.

For example, the optical waveguide may be designed such that the firstlight is individually directed to all of the point lights using multiplefirst light sources.

Alternatively, the optical waveguide may be designed such that the firstlight supplied from a small number of first light sources is directed toall of the point lights using a branch method.

Accordingly, the transparent backlight panel of the wearable display maybe advantageous in that point lights may be implemented such that lightfor all of the point lights has the same properties or in that the pointlights may be implemented so as to have different patterns depending onthe purpose thereof. That is, the transparent backlight panel accordingto the present invention may be used as a panel for displaying anarbitrary video image when the concept of a unit pixel in a generalimage panel is applied thereto.

Here, the characteristics of the first light supplied to each of themultiple point lights may be individually controlled based on amultiple-layer structure using multiple transparent backlight panels.

The multiple-layer structure will be described in detail with referenceto FIGS. 3 to 6.

Here, the second light for tracking the eye gaze of the user who wearsthe wearable display may have a wavelength that is harmless to the humanbody and available for eye tracking. That is, the second light may notbe limited to light having a specific wavelength, such as infrared rays.

Here, the second light may be projected using the point lights thatproject the first light, among the multiple point lights, or may beprojected using point lights other than the point lights that projectthe first light, among the multiple point lights.

That is, a single point light may project both the first light and thesecond light, and a point light for projecting the first light may beseparate from that for projecting the second light.

Also, in the method for providing a composite image based on opticaltransparency according to an embodiment of the present invention, thedegree of light concentration of any one of the first light and thesecond light is adjusted based on a micro-lens array, and the light, ofwhich the degree of light concentration is adjusted, is output at stepS220.

Here, the micro-lens array may be manufactured as a fixed type byfabricating micro-lenses, which have optical parameters adapted to thelocations of point lights distributed over the transparent backlightpanel and to the direction of light projected by the point lights.

Also, the micro-lens array may be configured with multiple lenses, thethicknesses of which are controllable in real time. For example, themicro-lens array may be configured with micro-lenses using polymermaterials.

Here, the multiple lenses may be individually controlled based on acontrol signal for each of multiple groups generated based on themultiple lenses.

The process of controlling each of the multiple lenses will be describedin detail with reference to FIGS. 12 to 16.

Here, the micro-lens array performs at least one of a convergencefunction and a divergence function, thereby adjusting the degree oflight concentration such that the first light has the same properties asnatural light. That is, because the wearable display based on opticaltransparency according to an embodiment of the present inventionvisually provides both a virtual image and an external image input fromthe outside of the display at the same time, the two images must beprovided so as to be naturally shown to the user's eyes. Accordingly,the first light inside the wearable display, which is to be output inorder to project the virtual image, may be adjusted using the micro-lensarray so as to have the same characteristics as natural light, whichaffects the projection of the external image onto a pupil of a user.

That is, because the micro-lens array is capable of controlling thedegree of light concentration of the first light, the area onto whichthe first light is projected may be variably controlled by adjusting thesense of the relative distance from the multiple point lights to theimage display panel.

Here, the micro-lens array performs at least one of a convergencefunction and a divergence function, whereby the degree of lightconcentration may be controlled so as to improve the transmissivity withwhich the second light penetrates through the image display panel and toimprove the collection rate at which the second light reflected from apupil of a user is collected.

Here, the image display panel may be formed of a light-transmissivematerial. For example, the image display panel may be configured with anLCD panel from which a backlight panel is eliminated, a transparent OLEDpanel, or the like.

Here, because the second light penetrating through the image displaypanel needs to be projected onto a pupil of the user whose eye gaze isto be tracked, the degree of light concentration may be adjusted usingthe micro-lens array in order to project as much second light aspossible onto a pupil of the user.

Here, among the multiple lenses, a lens, the refractive index of whichexceeds a user recognition level, may be deactivated.

For example, when a part of the micro-lens array is included in a user'sfield of view, because the projection of the image of the real worldoutside the wearable display may be distorted, the function of somelenses may be disabled in consideration of the refractive index.

Here, through selective masking, which defocuses the external imagebased on a change in the refractive index of the lens, the virtual imageoutput via the image display panel may be made more clearly visible.

Also, in the method for providing a composite image based on opticaltransparency according to an embodiment of the present invention, theeye gaze of the user is tracked at step S230 by collecting the secondlight reflected from a pupil of the user based on the optical waveguide.

Here, using the bidirectional propagation characteristic of a mediumforming the optical waveguide, while the second light is being outputfrom the multiple point lights, the second light, reflected from a pupilof the user, may be collected.

For example, when the second light that travels along the opticalwaveguide is projected onto an eye of a user, the second light reflectedtherefrom may be collected using the point lights that project thesecond light or point lights exclusively used for collecting thereflected second light. Here, the eye-tracking module according to anembodiment of the present invention may determine the direction of eyegaze of the user in consideration of the amount of the reflected andcollected second light and the pattern of the reflected second light,which is collected by the point lights.

Here, the reflected second light may be collected using the end part ofthe optical waveguide that is extended closer to the pupil of the user.

Here, in order to improve the efficiency of collection of the reflectedsecond light, the function of lenses forming the micro-lens array may becontrolled.

For example, the point lights for tracking the eye gaze of a user may beassumed to interfere with the user's field of view. In this case, thefunction of some lenses may be disabled such that the intensity of thesecond light projected by the point lights is somewhat reduced.

Also, in the method for providing a composite image based on opticaltransparency according to an embodiment of the present invention, theexternal image and the virtual image are combined based on the trackedeye gaze of the user and are provided to the user at step S240.

Here, the image display panel may be a module for creating andoutputting a virtual image. For example, the image display panel maycorrespond to a spatial light modulator, and may be configured with alight-transmissive material.

Accordingly, the external image penetrating through the image displaypanel and the virtual image output via the image display panel may besimultaneously shown to the user.

Here, the external image and the virtual image are simultaneously shownusing the wearable display, whereby the user may feel as if the twoimages were combined.

Here, the transparent backlight panel including the optical waveguide,the micro-lens array, and the image display panel may be included in thetransparent panel of the wearable display, which is located directly infront of a pupil of the user.

Generally, in conventional methods for tacking a user's eye, a lightsource for eye tracking is located in a diagonal direction relative to apupil of the user in the area outside the user's field of view in orderto avoid obscuring the user's view, and a sensor for receiving eyeinformation is also located outside the user's field of view. However,these conventional methods increase the volume and weight of a wearabledevice. Further, because the image of the eye acquired in the diagonaldirection is distorted, the accuracy of eye tracking may be reduced.

In order to solve these problems, the present invention proposes astructure in which the image information of the pupil of a user isacquired using a transparent backlight panel placed directly in front ofa pupil of the user, specifically, using the multiple point lightsincluded in the transparent backlight panel. Accordingly, the volume andweight of the wearable display may be reduced, and the accuracy of eyetracking may be improved.

Here, the transparent panel may be in the form of a flat surface or acurved surface.

Here, the wearable display to which the transparent panel in the form ofa flat or curved surface is applied will be described in detail withreference to FIGS. 18 and 19.

Also, in the method for providing a composite image based on opticaltransparency according to an embodiment of the present invention, thefocus of a composite image projected onto a pupil of the user iscalibrated using an additional micro-lens array located between theimage display panel and the pupil of the user.

For example, the focus of the projected image may not be formed on aretina because of the characteristics of the eyesight of the user.Accordingly, in order to form the focus of the projected image on theretina, calibration may be performed using the additional micro-lensarray.

Also, a point-light panel based on an optical waveguide, an energyconcentration or distribution pattern based on an array of individuallycontrollable micro-lenses, and an eye-tracking module using the abovetwo modules may be implemented so as to operate independently, and maythen be applied to the final implementation prototype.

For example, when the above three main modules are applied to asee-closed wearable display, it is possible to implement a Head-MountedDisplay (HMD) that is thinner and lighter than a conventional display,such as Oculus VR's KD2 HMD and Sony's Morpheus HMD. Also, because theentire area of the optical waveguide point-light panel may be used as aninput/output sensor unit for eye-tracking light, eye tracking may bemore accurately implemented.

Also, in the method for providing a composite image based on opticaltransparency according to an embodiment of the present invention,various kinds of information generated during the above-describedprocess of providing a composite image based on optical transparency isstored in a separate storage module.

Through the above-described method for providing a composite image,wearable display technology through which image information filling auser's field of view may be provided based on optical transparency usinga light and small module resembling general eyeglasses may be provided.

Also, the method of controlling energy emission by each point light,which may overcome the limitation of the pin-light array, is provided,whereby the visual quality (contrast, color quality, intensity, focusalignment, and the like) of an image output via an eyeglasses-typedisplay may be improved.

Also, an eye-tracking module with a minimum volume may be embedded in aneyeglasses-type display, and the pattern of movement of an eye locatedin front thereof or off to one side may be tracked.

FIGS. 3 to 6 are views that show an example of design of an opticalwaveguide based on multiple layers according to the present invention.

Referring to FIGS. 3 to 6, when an optical waveguide in a transparentbacklight panel is designed in order to arrange a plurality of firstpoint lights for emitting first light and a plurality of second pointlights for emitting second light according to the present invention, theoptical waveguide may be designed using multiple layers in order toindividually control the point lights.

For example, the multiple-layer structure illustrated in FIG. 6 may bedesigned by layering the transparent backlight panel 330 shown in FIG. 3and the transparent backlight panels 430 and 530 shown in FIGS. 4 and 5,which are of the same type as the transparent backlight panel 330. Here,the transparent backlight panel 330, illustrated in FIG. 3, includes afirst optical waveguide 311 connected with a first light source 310, afirst point light 312 connected with the first optical waveguide 311, asecond optical waveguide 312 connected with a second light source 320,and a second point light 322 connected with the second optical waveguide312, as illustrated in FIG. 3.

The multiple-layer structure may be advantageous in that thecharacteristics of light energy, such as intensity, wavelength, and thelike, for each of all point lights may be individually controlled usingeach light source connected therewith. Also, when each optical waveguideis designed, the amount of light delivered to a single point light maybe adjusted by changing the diameter of the optical waveguide.

FIG. 7 is a view that shows an example of design of an optical waveguidebased on a single layer according to the present invention.

Referring to FIG. 7, the thickness or diameter of an optical waveguideformed inside a transparent backlight panel 770 according to the presentinvention may be a few micrometers (μm).

Accordingly, wire, such as a general electronic circuit, is not visiblein the delivery path between a light source and a point light.Therefore, the problem in which light is blocked when an opticallytransparent system is implemented may not occur.

Also, because the transparent backlight panel in which an opticalwaveguides are formed is placed very close to the eye of a user, theimage of optical waveguides in the form of lines is not focused on theretina, whereby transparency may be maintained.

Accordingly, a transparent backlight panel 770 may be implemented usingonly a single layer according to need, as shown in FIG. 7, without usingthe multiple-layer structure illustrated in FIG. 6.

FIGS. 8 to 11 are views that show an example of design of shared ordistributed optical waveguides and an energy output method based thereonaccording to the present invention.

Referring to FIGS. 8 to 11, the optical waveguide according to thepresent invention may be designed such that all point lights arecontrolled using a single first light source 810 and a single secondlight source 820, as shown in FIG. 8, or such that all point lights aredivided into a small number of groups and controlled based on multiplefirst light sources 911 and 912 and multiple second light sources 921,922 and 923, as shown in FIG. 9.

First, the example in FIG. 8 shows that the single first light sourcesupplies first light to all point lights connected therewith. Here, eachof the first light source 810 and the second light source 820corresponds to a single type of light, but light output to the multiplepoint lights may be imparted with same characteristics or differentcharacteristics by changing the shapes of respective optical waveguidesconnected with the point lights. For example, the amount of lightsupplied to each of the point lights may be varied by changing thediameter of the optical waveguide connected therewith.

Also, the example in FIG. 9 shows that all of the point lights aredivided into two or three groups and light is supplied thereto. Here,using the first light sources 911 and 912 or the second light sources921, 922 and 923, which are connected with the respective groups ofpoint lights, the light output by each group may be imparted withdifferent characteristics.

For example, the first light and the second light are supplied only tothe first point lights 1010 and the second point lights 1020 placed inthe center part, among all point lights, and some point lights 1030placed at the border may be turned off by blocking the supply of lightthereto, as shown in FIG. 10.

In another example, the first light and the second light may be suppliedonly to the first point lights 1110 and the second point lights 1120,which are centered horizontally and vertically, and the remaining pointlights 1130 may be turned off by blocking the supply of light thereto,as shown in FIG. 11.

FIGS. 12 to 16 are views that show an example of the method ofcontrolling multiple lenses in a micro-lens array according to thepresent invention.

Referring to FIGS. 12 to 16, multiple lenses 1220 included in themicro-lens array 1210 illustrated in FIG. 12 may be fixed-type lenseswith previously designed optical parameters. Here, the opticalparameters may have values optimized for specific eyesight, the opticalwaveguide, and the characteristics of an image display panel, and may beset so as to satisfy the purpose of the system.

Also, the multiple lenses 1220 according to an embodiment of the presentinvention may be deformable micro-lenses, the thicknesses of which maybe controlled in real time.

In this case, the multiple lenses 1220 may be controlled in such a waythat all of the multiple lenses 1220 are connected with a transparentcontrol circuit 1311 corresponding to a single lens control module, andall of the multiple lenses 1220 are transformed and controlled using asingle control signal, as shown in FIG. 13.

Alternatively, the multiple lenses 1220 may be divided into a certainnumber of groups, and the respective groups may be controlled bycorresponding ones of multiple lens control modules 1410, 1420 and 1430,as shown in FIG. 14, whereby the multiple lenses 1220 may be controlledin greater variety of patterns.

Here, the transparent control circuits 1411, 1421 and 1431 fordelivering control signals to the respective groups may be designed soas not to impede the travel of light.

Also, although not illustrated in the drawings, the multiple lenses 1220may be controlled individually. Here, the transparent control circuitfor delivering a control signal to each of the lenses may also beimplemented so as not to impede the travel of light.

Also, the micro-lens array according to the present invention may useselective masking by changing the refractive index of each lens. Forexample, an external image projected from the outside may be shown via atransparent panel even in the area in which a virtual image is displayedin the image display panel, whereby the virtual image is superimposed onthe external image. Accordingly, in order to clearly show the virtualimage, the refractive index of the lens located in the correspondingpart is controlled in order to defocus the external image projected ontothe virtual image display area, whereby the external image may beconcealed.

That is, as illustrated in FIGS. 15 to 16, lenses 1510 and 1610 locatedin the center part of the micro-lens array, in which the virtual imageis expected to be displayed, are controlled so as to be in a maskingstate by changing the refractive index thereof, and the remaining lenses1520 and 1620 may be controlled so as to allow the projection of theexternal image therethrough.

FIG. 17 is a view that shows layering of the transparent backlight panelillustrated in FIG. 6 and the micro-lens array illustrated in FIG. 14.

Referring to FIG. 17, optical-waveguide-based transparent backlightpanels 330, 430 and 530 and a micro-lens array are integrated into thetransparent panel of a wearable display according to an embodiment ofthe present invention, whereby the transparent panel may be produced inthe form of a single thin lens for eyeglasses.

Here, the transparent backlight panel or the micro-lens arrayillustrated in FIG. 17 may be produced in various forms depending on thepurpose thereof. Accordingly, the wearable display according to thepresent invention may also be produced in various forms.

FIG. 18 is a view that shows the structure of a wearable display in theform of a flat surface according to an embodiment of the presentinvention.

Referring to FIG. 18, a wearable display in the form of a flat surfaceincludes a transparent backlight panel 1810, a micro-lens array 1840,eye-tracking modules 1810 and 1850, and an image display panel 1850.

The transparent backlight panel 1810 enables first light to be suppliedfrom a first light source 1820 to multiple point lights through a firstoptical waveguide 1821 and enables second light to be supplied from asecond light source 1830 to multiple point lights through a secondoptical waveguide 1831.

Here, although not illustrated in FIG. 18, the first light supplied bythe first light source 1820 and the second light supplied by the secondlight source 1830 may share the same optical waveguide when supplied tomultiple point lights. That is, the first optical waveguide and thesecond optical waveguide illustrated in FIG. 18 may be combined, and thefirst light and the second light may be supplied using the singlecombined waveguide.

Here, the first light supplied by the first light source 1820 is notrandomly reflected, but travels only along the previously designed firstoptical waveguide 1821, whereby the problem in which light cannotmaintain an equal brightness and wavelength by being totally internallyreflected and scattered when the existing point-light source pattern isused may be solved.

For example, the optical waveguide may be designed and manufacturedusing the method of designing and manufacturing an Integrated Circuit(IC) board or a press-printing method for forming multiple layers. Thesemanufacturing methods are commonly used in optical communications fieldsor semiconductor fabrication fields, but may also be used to solve theproblems resulting from forming the pattern of point lights in the fieldof a wearable display that is capable of providing a composite image, asin the present invention.

Here, the first light supplied by the first light source 1820 may bevisible rays for showing a virtual image generated in the wearabledisplay to a user by projecting the same.

Here, the intensity of the first light supplied to each of multiplefirst point lights may be individually controlled by adjusting thediameters of some of the multiple paths corresponding to the firstoptical waveguide 1821.

For example, the first waveguide 1821 may be designed such that thefirst light is independently directed to all of the point lightsconnected with the first optical waveguide 1821 using multiple firstlight sources 1820.

Alternatively, the first optical waveguide 1821 may be designed suchthat, using a small number of first light sources 1820, the first lightis directed to all of the point lights connected with the first opticalwaveguide 1821 through a branch method.

Accordingly, the transparent backlight panel 1810 of the wearabledisplay may be advantageous in that point lights may be implemented suchthat light for all of the point lights has the same properties or inthat the point lights may be implemented so as to have differentpatterns depending on the purpose. That is, the transparent backlightpanel 1810 according to the present invention may be used as a panel fordisplaying an arbitrary video image when the concept of a unit pixel ina general image panel is applied thereto.

Here, the characteristics of the first light supplied to each of themultiple point lights may be individually controlled based on amultiple-layer structure using the multiple transparent backlight panels1810.

Because the multiple-layer structure has been described with referenceto FIGS. 3 to 6, a description thereof will be omitted in FIG. 18.

Here, the second optical waveguide 1831 may have the samecharacteristics as the above-described first optical waveguide 1821.That is, the second optical waveguide 1831 may differ from the firstoptical waveguide 1821 in that the first optical waveguide 1821 is usedto supply the first light from the first light source 1820 whereas thesecond optical waveguide 1831 is used to supply the second light fromthe second light source 1830.

For example, the second light source 1830 may be used for tracking theeye gaze of the user who wears the wearable display, and may supplylight having a wavelength that is harmless to the human body andavailable for eye tracking. That is, the second light may not be limitedto light having a specific wavelength, such as infrared rays.

Here, the second light may be projected using point lights other thanthe point lights that project the first light, as shown in FIG. 18, ormay be projected using the point lights that project the first light.

That is, a single point light may project both the first light and thesecond light, and a point light for projecting the first light may beseparate from that for projecting the second light.

The micro-lens array 1840 adjusts the degree of light concentration ofany one of the first light and the second light, thereby outputtinglight of which the degree of light concentration is adjusted.

Here, the micro-lens array 1840 may be manufactured as a fixed type byfabricating micro-lenses, which have optical parameters adapted to thelocations of the multiple point lights distributed over the transparentbacklight panel 1810 and to the direction of light projected by themultiple point lights.

Also, the micro-lens array 1840 may be configured with multiple lenses1841, the thicknesses of which are controllable in real time. Forexample, the micro-lens array 1840 may be configured with micro-lensesusing polymer materials.

Here, the multiple lenses 1841 may be individually controlled based on acontrol signal for each of multiple groups generated based on themultiple lenses 1841.

The process of controlling each of the multiple lenses 1841 has beendescribed with reference to FIGS. 12 to 16, and thus a descriptionthereof will be omitted in FIG. 18.

Here, the micro-lens array 1840 performs at least one of a convergencefunction and a divergence function, thereby adjusting the degree oflight concentration such that the first light has the same properties asnatural light. That is, because the wearable display based on opticaltransparency according to an embodiment of the present inventionvisually provides both a virtual image and an external image input fromoutside the display at the same time, the two images must be provided soas to be naturally shown to the user's eyes. Accordingly, using themicro-lens array 1840, the first light inside the wearable display,which is to be output in order to project the virtual image, may beadjusted so as to have the same characteristics as natural light, whichaffects the projection of the external image onto a pupil of a user.

That is, because the micro-lens array 1840 is capable of controlling thedegree of light concentration of the first light output by the firstlight source 1820, the area onto which the first light is projected maybe variably controlled by adjusting the sense of a relative distancefrom the multiple point lights for emitting the first light to the imagedisplay panel 1850.

The eye-tracking module tracks the eye gaze of a user by collecting thesecond light reflected from a pupil 1860 of the user based on theoptical waveguide.

Here, although a specific eye-tracking module is not illustrated in FIG.18, the function of an eye-tracking module may be performed based on thesecond light source 1830, the second optical waveguide 1831 included inthe transparent backlight panel 1810, and the multiple point lights,illustrated in FIG. 18, whereby the line of sight from a pupil 1860 ofthe user may be tracked.

Here, the micro-lens array 1840 performs at least one of a convergencefunction and a divergence function, whereby the degree of lightconcentration may be controlled so as to improve the transmissivity withwhich the second light penetrates through the image display panel 1850and to improve the collection rate at which the second light reflectedfrom the pupil 1860 of a user is collected.

Here, the image display panel 1850 is a module for outputting thevirtual image to be combined with the external image. The image displaypanel 1850 may be formed of a light-transmissive material. For example,the image display panel may be configured with an LCD panel from which abacklight panel is eliminated, a transparent OLED panel, or the like.

Here, because the second light penetrating through the image displaypanel 1850 needs to be projected onto a pupil 1860 of the user whose eyegaze is to be tracked, the degree of light concentration may be adjustedusing the micro-lens array 1840 in order to project as much second lightas possible onto the pupil 1860 of the user.

Here, using the bidirectional propagation characteristic of a mediumforming the optical waveguide, while the second light is directed to thepupil 1860 of the user, the second light reflected therefrom may becollected.

For example, when the second light that travels along the second opticalwaveguide 1831 is projected onto the eye of a user, the second lightreflected therefrom may be collected using the point lights that projectthe second light or point lights exclusively used for collecting thereflected second light. Here, the eye-tracking module according to anembodiment of the present invention may determine the direction of theeye gaze of the user in consideration of the amount and pattern of thereflected and collected second light.

Here, among the multiple lenses 1841, a lens, the refractive index ofwhich exceeds a user recognition level, may be deactivated.

For example, when a part of the micro-lens array is included in theuser's field of view, because the projection of the image of the realworld outside the wearable display may be distorted, the functions ofsome lenses may be disabled in consideration of the refractive index.

Here, through selective masking, which defocuses the external imagebased on a change in the refractive index of the lens, the virtual imageoutput via the image display panel 1850 may be made more clearlyvisible.

Here, the image display panel 1850 may be a module for creating anddisplaying a virtual image. For example, the image display panel 1850may correspond to a spatial light modulator (SLM), and may be configuredwith a light-transmissive material.

Accordingly, the external image penetrating through the image displaypanel 1850 and the virtual image output via the image display panel 1850may be simultaneously shown to the user.

Here, the external image and the virtual image are simultaneously shownusing the wearable display, whereby the user may feel as if the twoimages were combined.

Here, the transparent backlight panel 1810 including at least one of thefirst optical waveguide 1821 and the second optical waveguide 1831, themicro-lens array 1840, and the image display panel 1850 may be includedin the transparent panel of the wearable display, which is locateddirectly in front of a pupil of the user.

Generally, in the conventional methods for tracking a user's eye, alight source for eye tracking is located in a diagonal directionrelative to a pupil of the user in the area outside the user's field ofview in order to avoid obscuring the user's view, and a sensor forreceiving eye information is also located outside the user's field ofview. However, these conventional methods increase the volume and weightof a wearable device. Further, because the image of the eye acquired inthe diagonal direction is distorted, the accuracy of eye tracking may bereduced.

In order to solve these problems, the present invention proposes astructure in which the image information of a pupil 1860 of a user isacquired using a transparent backlight panel 1810 placed directly infront of the pupil of the user, specifically, using the multiple pointlights included in the transparent backlight panel 1810, as shown inFIG. 18. Accordingly, the volume and weight of the wearable display maybe reduced, and the accuracy of eye tracking may be improved.

Here, the transparent panel may be in the form of a flat surface, asshown in FIG. 18, or may be in the form of a curved surface.

Here, the eye gaze of the user is tracked by collecting the second lightreflected from a pupil 1860 of the user based on the multiple pointlights and the second optical waveguide 1831. However, when the multiplepoint lights generate interference in the user's field of view, thereflected second light may be collected using the end part of the secondoptical waveguide 1831, which extends closer to the pupil 1860 of theuser than the multiple point lights.

Here, in order to improve the efficiency of collection of the reflectedsecond light, the function of the lenses 1841 forming the micro-lensarray 1840 may be controlled.

For example, it may be assumed that the point lights for tracking theeye gaze of a user, other than the point lights for projecting the firstlight, interfere with the user's field of view. In this case, thefunction of the lenses may be disabled in order to somewhat reduce theintensity of the second light emitted by the point lights for eyetracking.

Using the above-described wearable display based on opticaltransparency, provided is wearable display technology, through whichimage information filling a user's field of view may be provided basedon optical transparency using a light and small module resemblinggeneral eyeglasses.

Also, the method of controlling energy emission by each point light,which may overcome the limitation of the pin-light array, is provided,whereby the visual quality (contrast, color quality, intensity, focusalignment, and the like) of an image output via an eyeglasses-typedisplay may be improved.

Also, an eye-tracking module with a minimum volume may be embedded in aneyeglasses-type display, and the pattern of movement of an eye locatedin front thereof or off to one side may be tracked.

FIG. 19 is a view that shows the structure of a wearable display havingthe form of a curved surface according to an embodiment of the presentinvention.

Referring to FIG. 19, the shape of the transparent panel of a wearabledisplay according to an embodiment of the present invention is a curvedsurface, unlike the flat surface illustrated in FIG. 18.

Here, when the transparent backlight panel 1910 in the form of a curvedsurface, illustrated in FIG. 19, is used, the field of view, in which anexternal image or a virtual image is shown through the pupils 1960 of auser, may become wider.

That is, in the transparent backlight panel 1810 in the form of a flatsurface, illustrated in FIG. 18, the distance from a pupil 1860 of auser to each of multiple point lights increases when moving from thecenter of the transparent backlight panel 1810 to the border thereof

However, because the present invention may individually control lightemission by the respective point lights by varying optical waveguides,even when the transparent backlight panel 1810 is implemented in theform of a flat surface, as shown in FIG. 18, the above problem may besolved by increasing the diameter of an optical waveguide closer to theborder area of the transparent backlight panel 1810 or by adjusting theintensity of light using a light source.

When the transparent backlight panel 1910 is implemented in the form ofa curved surface so as to be suitable for the curvature of an eyeball ora retina, as shown in FIG. 19, the distance from a pupil 1960 of a userto each of the multiple point lights included in the transparentbacklight panel 1910 may be maintained the same.

The method of transmitting light energy proposed in the presentinvention may be widely applied to an optical system having an arbitrary3D shape and volume when it is possible to design an optical waveguideinside the optical module. Also, because the wearable display based onoptical transparency according to an embodiment of the present inventionmay enable an optical waveguide to be embedded in the curved (aspheric)surface in the form of an eyeglasses lens, it may be widely applied toan optical system having an arbitrary 3D shape and volume.

FIG. 20 is a view that shows the structure of a wearable displayincluding an additional micro-lens array according to an embodiment ofthe present invention.

Referring to FIG. 20, an additional micro-lens array 2060 according toan embodiment of the present invention is placed between an imagedisplay panel 2050 and an eyeball 2070.

This structure may solve a problem in which the projected image is notfocused on the retina due to the eyesight of a user.

According to the conventional art, the focus of the sight of a user isbasically assumed to be infinitely distant (that is, the eye lens isassumed to be relaxed). However, when it is necessary to visualize andmanipulate a 3D image in a near-body space within a distance of 1 m froma user's view point, like the manipulation of a 3D Graphical UserInterface (GUI), the thickness of an eye lens is increased in order tosee an item at a near distance, whereby the image projected onto theretina may be defocused.

Therefore, the present invention arranges the additional micro-lensarray 2060 for calibration, as shown in FIG. 20, whereby the focalposition may be calibrated.

According to the present invention, technology for a wearable displaythat is capable of providing image information filling a user's field ofview based on optical transparency using a light and small moduleresembling general eyeglasses may be provided.

Also, the present invention may improve visual quality, such ascontrast, color quality, intensity, focus alignment, and the like, of animage output via an eyeglasses-type display by providing technology forcontrolling energy emission by each point light source, which mayovercome the limitation of a pin-light array.

Also, the present invention may provide an eye-tracking module with aminimum volume that may be embedded in an eyeglasses-type display andthat may track the pattern of movement of eyes located in front thereofor off to one side.

As described above, the method for providing a composite image based onoptical transparency according to the present invention and theapparatus for the same are not limitedly applied to the configurationsand operations of the above-described embodiments, but all or some ofthe embodiments may be selectively combined and configured, so that theembodiments may be modified in various ways.

What is claimed is:
 1. A method for providing a composite image based onoptical transparency, comprising: supplying first light of a first lightsource for projecting a virtual image and second light of a second lightsource for tracking an eye gaze of a user to multiple point lights basedon an optical waveguide having a bidirectional propagationcharacteristic, the multiple point lights projecting the first light andthe second light; adjusting a degree of light concentration of any oneof the first light and the second light projected by the multiple pointlights, using a micro-lens array and outputting the first light or thesecond light, of which the degree of light concentration is adjusted;collecting the second light reflected from a pupil of the user based onthe optical waveguide, thereby tracking the eye gaze of the user; andcombining an external image with the virtual image based on the trackedeye gaze and providing the combined image to the user, wherein atransparent backlight panel including the optical waveguide, themicro-lens array, and a transparent image display panel for displayingthe virtual image are included in a transparent panel of a wearabledisplay, which is located directly in front of the pupil of the user. 2.The method of claim 1, wherein supplying the first light and the secondlight comprises individually controlling an intensity of the first lightsupplied to each of the multiple point lights by adjusting diameters ofsome of multiple paths corresponding to the optical waveguide.
 3. Themethod of claim 2, wherein supplying the first light and the secondlight comprises individually controlling a characteristic of the firstlight supplied to each of the multiple point lights based on amultiple-layer structure using multiple transparent backlight panels. 4.The method of claim 1, wherein the micro-lens array is configured withmultiple lenses, thicknesses of which are controllable in real time. 5.The method of claim 4, wherein the multiple lenses are individuallycontrolled in response to a control signal for each of multiple groupsgenerated based on the multiple lenses.
 6. The method of claim 1,further comprising: calibrating a focus of a composite image projectedonto the pupil of the user using an additional micro-lens array locatedbetween the image display panel and the pupil of the user.
 7. The methodof claim 1, wherein the transparent panel of the wearable display is ina form of a flat surface or a curved surface.
 8. The method of claim 1,wherein outputting the first light or the second light, of which thedegree of light concentration is adjusted, comprises: performing, by themicro-lens array, at least one of a convergence function and adivergence function, thereby adjusting the degree of light concentrationsuch that the first light has a same property as natural light; andperforming, by the micro-lens array, at least one of the convergencefunction and the divergence function, thereby adjusting the degree oflight concentration such that a transmissivity with which the secondlight penetrates through the image display panel is increased and suchthat a collection rate at which the second light reflected from thepupil of the user is collected is increased.
 9. The method of claim 4,wherein outputting the first light or the second light, of which thedegree of light concentration is adjusted, comprises: deactivating alens, a refractive index of which exceeds a user recognition level,among the multiple lenses.
 10. The method of claim 1, wherein trackingthe eye gaze of the user comprises collecting the reflected second lightusing an end part of the optical waveguide that is extended so as to becloser to the pupil of the user.
 11. A wearable display based on opticaltransparency, comprising: a transparent backlight panel for supplyingfirst light of a first light source for projecting a virtual image,which is to be combined with an external image, and second light of asecond light source for tracking an eye gaze of a user to multiple pointlights based on an optical waveguide having a bidirectional propagationcharacteristic, the multiple point lights projecting the first light andthe second light; a micro-lens array for adjusting a degree of lightconcentration of any one of the first light and the second lightprojected by the multiple point lights and outputting the first light orthe second light, of which the degree of light concentration isadjusted; an eye-tracking module for tracking the eye gaze of the userby collecting the second light reflected from a pupil of the user basedon the optical waveguide; and an image display panel for displaying thevirtual image, wherein the transparent backlight panel, the micro-lensarray, and the image display panel are included in a transparent panelof the wearable display that is located directly in front of the pupilof the user.
 12. The wearable display of claim 11, wherein thetransparent backlight panel individually controls an intensity of thefirst light supplied to each of the multiple point lights by adjustingdiameters of some of multiple paths corresponding to the opticalwaveguide.
 13. The wearable display of claim 12, wherein acharacteristic of the first light supplied to each of the multiple pointlights is individually controlled based on a multiple-layer structureusing multiple transparent backlight panels.
 14. The wearable display ofclaim 11, wherein the micro-lens array is configured with multiplelenses, thicknesses of which are controllable in real time.
 15. Thewearable display of claim 14, wherein the multiple lenses areindividually controlled in response to a control signal for each ofmultiple groups generated based on the multiple lenses.
 16. The wearabledisplay of claim 11, wherein the transparent panel of the wearabledisplay further includes an additional micro-lens array, located betweenthe image display panel and the pupil of the user, for calibrating afocus of a composite image to be projected onto the pupil of the user.17. The wearable display of claim 11, wherein the transparent panel ofthe wearable display is in a form of a flat surface or a curved surface.18. The wearable display of claim 11, wherein the eye-tracking modulecollects the reflected second light using an end part of the opticalwaveguide extended so as to be closer to the pupil of the user.
 19. Amethod for providing a composite image based on optical transparency,comprising: supplying first light of a first light source for projectinga virtual image and second light of a second light source for trackingan eye gaze of a user to multiple point lights based on an opticalwaveguide having a bidirectional propagation characteristic, themultiple point lights projecting the first light and the second light;adjusting a degree of light concentration of any one of the first lightand the second light projected by the multiple point lights, using amicro-lens array and outputting the first light or the second light, ofwhich the degree of light concentration is adjusted; collecting thesecond light reflected from a pupil of the user based on the opticalwaveguide, thereby tracking the eye gaze of the user; and combining anexternal image with the virtual image based on the tracked eye gaze andproviding the combined image to the user, wherein the micro-lens arrayis configured with multiple lenses, and the multiple lenses areindividually controlled in response to a control signal for each ofmultiple groups generated based on the multiple lenses.
 20. A method forproviding a composite image based on optical transparency, comprising:supplying first light of a first light source for projecting a virtualimage and second light of a second light source for tracking an eye gazeof a user to multiple point lights based on an optical waveguide havinga bidirectional propagation characteristic, the multiple point lightsprojecting the first light and the second light; adjusting a degree oflight concentration of any one of the first light and the second lightprojected by the multiple point lights, using a micro-lens array andoutputting the first light or the second light, of which the degree oflight concentration is adjusted; collecting the second light reflectedfrom a pupil of the user based on the optical waveguide, therebytracking the eye gaze of the user; and combining an external image withthe virtual image based on the tracked eye gaze and providing thecombined image to the user, wherein the micro-lens array is configuredwith multiple lenses, and wherein outputting the first light or thesecond light, of which the degree of light concentration is adjusted,comprises deactivating a lens, a refractive index of which exceeds auser recognition level, among the multiple lenses.